[time-nuts] LightSquared is back now called Ligado

[Dana Whitlow]

Seems to me that both GPS receivers and Ligado's transmitters are going to
need the
"brick-wall" filters.  I wonder how lossy such filters will be when sized
to fit in handheld
GPS receivers, smart phones, and (especially) GPS watches.

On the other hand, it may be that many time-nuts will not live close enough
to any of
Ligado's terrestrial sites to be appreciably bothered.

It's a difficult situation- we won't know how big the problem is until
Ligado goes on the air,
yet the time to complain is now, before any rulemaking occurs or
construction permits are
granted.

Test results on a wide variety of commonly-used GPS receivers would sure be
nice.

Dana


On Fri, Apr 17, 2020 at 6:14 PM djl <djl at montana.com> wrote:

> And the competition has/is putting up a gazillion cubesats to screw up
> another of my little pleasures, astronomy. Bah. It's enough to make you
> want to go out and stand right next to somebody.
> Don
>
> On 2020-04-17 14:37, Scott McGrath wrote:
> > That was +9.8 on the terrrestrial microcell transmitters,
> >
> > Yes this seems to have been sold with the assurance that the magic
> > brickwall filters with 100db/octave slope will be included in every
> > one.
> >
> > But the asian manufacturer of said devices will neglect to include
> > them.... and juice the power a wee bit to say +23...
> >
> > Of course this will hose every GPS system for miles around and for
> > those of us who fly our multi thousand investment in ADS-B will be
> > rendered useless as the ADS-B still uses L1.    In our club’s Cessna
> > 172 the new ADS-B in/out compliant radio stack was 20,000 as we are
> > close to a lot of controlled airspace.
> >
> >
> >   I dropped a note to AOPA on this.   Because remember the entire
> > airway system is now supposed to be managed by aircraft exchanging
> > position, bearing altitude and rate of climb dynamically to each other
> > and ground stations instead of todays radar based system.
> >
> > And say goodbye to our GPSDO’s
> >
> > On Apr 17, 2020, at 2:59 PM, Bob kb8tq <kb8tq at n1k.org> wrote:
> >
> > Hi
> >
> > Was that +9.8 or -98 dbm ? :)
> >
> > At -98 they probably *could* coexist with GPS. Not real clear how well
> > there
> > system would work at that level though.
> >
> > Bob
> >
> >> On Apr 17, 2020, at 1:37 PM, Scott McGrath <scmcgrath at gmail.com>
> >> wrote:
> >>
> >> Supposedly lowering Tx power on terrestrial network from +23 DBm to
> >> +9.8 DBm will make everything better.  Ajit Pai is listening only to
> >> carriers and ignoring DoD who is stating it will significantly degrade
> >> and/or make useless the GPS system.
> >>
> >> Not to mention ADS-B which was installed at great expense by the
> >> private and commercial aviation systems. And is totally dependent on
> >> the GPS segments most affected by Ligado
> >>
> >> Read and weep
> >>
> >>
> https://arstechnica.com/tech-policy/2020/04/fcc-to-approve-5g-network-despite-military-saying-it-will-harm-gps/
> >>
> >>
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> --
> Dr. Don Latham  AJ7LL
> PO Box 404, Frenchtown, MT, 59834
> VOX: 406-626-4304
>
>
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